BUCKHANNON, W.Va. - Federal officials say the explosion and fire that killed 12 men in a West Virginia mine was set off by a lightning strike.

Relatives of the miners who died at the Sago Mine rejected the conclusion, which was presented to them Wednesday by the Mine Safety and Health Administration, the Pittsburgh Post-Gazette reported. Scientists concluded that lightning created a magnetic field that penetrated deep into the mine.

"They're staffed with industry insiders and they police themselves and they're no longer effective," Sara Bailey, daughter of one of the dead miners, said of the MSHA.

The explosion left 13 men trapped underground. By the time rescuers reached them, only one was still alive.

The report chastised International Coal Group, which owns the mine, for a number of safety violations. The MSHA said, for example, that some breathing devices had not been tested, although the report said that even in the best circumstances the men would have exhausted their oxygen before they were rescued.